Fix devirtualization issues with IlGeneratorMethodDetails

When storing a particular variety of IlGeneratorMethodDetails into
MethodToBeCompiled, the code uses operator = which transmutes the existing
generic IlGeneratorMethodDetails (the base class) into a derived class
similar to the parameter that is passed in, by using placement new.
The expectation is that any call off the generic IlGeneratorMethodDetails
object stored in MethodToBeCompiled is going to be a virtual call.
However, the C++ compiler is allowed to devirtualize calls and if that
occurs, the JIT is going to invoke the implementation in the generic
IlGeneratorMethodDetails.

The solution introduced by this commit is to use an object factory
that builds a specific IlGeneratorMethodDetails at a designated address and
returns a pointer to that address which is then stored in MethodToBeCompiled.

Signed-off-by: Marius Pirvu <[email protected]>

runtime/compiler/trj9/control/MethodToBeCompiled.cpp

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2016 IBM Corp. and others
+ * Copyright (c) 2000, 2018 IBM Corp. and others
  *
  * This program and the accompanying materials are made available under
  * the terms of the Eclipse Public License 2.0 which accompanies this
@@ -50,7 +50,7 @@ TR_MethodToBeCompiled *TR_MethodToBeCompiled::allocate(J9JITConfig *jitConfig)
 
 void TR_MethodToBeCompiled::initialize(TR::IlGeneratorMethodDetails & details, void *oldStartPC, CompilationPriority p, TR_OptimizationPlan *optimizationPlan)
    {
-   _methodDetails = details;
+   _methodDetails = TR::IlGeneratorMethodDetails::clone(_methodDetailsStorage, details);
    _optimizationPlan = optimizationPlan;
    _next = NULL;
    _oldStartPC = oldStartPC;

runtime/compiler/trj9/control/MethodToBeCompiled.hpp

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2016 IBM Corp. and others
+ * Copyright (c) 2000, 2018 IBM Corp. and others
  *
  * This program and the accompanying materials are made available under
  * the terms of the Eclipse Public License 2.0 which accompanies this
@@ -52,7 +52,7 @@ struct TR_MethodToBeCompiled
    void initialize(TR::IlGeneratorMethodDetails & details, void *oldStartPC, CompilationPriority p, TR_OptimizationPlan *optimizationPlan);
 
    TR::Monitor *getMonitor() { return _monitor; }
-   TR::IlGeneratorMethodDetails & getMethodDetails(){ return _methodDetails; }
+   TR::IlGeneratorMethodDetails & getMethodDetails(){ return *_methodDetails; }
    bool isDLTCompile()   { return getMethodDetails().isMethodInProgress(); }
    bool isCompiled();
    bool isJNINative();
@@ -62,7 +62,8 @@ struct TR_MethodToBeCompiled
 
 
    TR_MethodToBeCompiled *_next;
-   TR::IlGeneratorMethodDetails _methodDetails;
+   TR::IlGeneratorMethodDetails _methodDetailsStorage;
+   TR::IlGeneratorMethodDetails *_methodDetails;
    void                  *_oldStartPC;
    void                  *_newStartPC;
    TR::Monitor *_monitor;

runtime/compiler/trj9/ilgen/IlGeneratorMethodDetails.hpp

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2016 IBM Corp. and others
+ * Copyright (c) 2000, 2018 IBM Corp. and others
  *
  * This program and the accompanying materials are made available under
  * the terms of the Eclipse Public License 2.0 which accompanies this
@@ -50,8 +50,8 @@ class OMR_EXTENSIBLE IlGeneratorMethodDetails : public J9::IlGeneratorMethodDeta
    IlGeneratorMethodDetails(const TR::IlGeneratorMethodDetails & other) :
       J9::IlGeneratorMethodDetailsConnector(other) {}
 
-   IlGeneratorMethodDetails & operator=(const TR::IlGeneratorMethodDetails & other);
    };
+
 }
 
 

runtime/compiler/trj9/ilgen/J9IlGeneratorMethodDetails.cpp

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2016 IBM Corp. and others
+ * Copyright (c) 2000, 2018 IBM Corp. and others
  *
  * This program and the accompanying materials are made available under
  * the terms of the Eclipse Public License 2.0 which accompanies this
@@ -35,47 +35,35 @@
 #include "ilgen/J9ByteCodeIlGenerator.hpp"
 #include "trj9/env/VMJ9.h"
 
-namespace TR
-{
-
-IlGeneratorMethodDetails & IlGeneratorMethodDetails::operator=(const TR::IlGeneratorMethodDetails & other)
-   {
-   return self()->J9::IlGeneratorMethodDetailsConnector::operator=(other);
-   }
-
-}
-
 
 
 namespace J9
 {
 
-TR::IlGeneratorMethodDetails &
-IlGeneratorMethodDetails::operator=(const TR::IlGeneratorMethodDetails & other)
+TR::IlGeneratorMethodDetails *
+IlGeneratorMethodDetails::clone(TR::IlGeneratorMethodDetails &storage, const TR::IlGeneratorMethodDetails & other)
    {
-   // The purpose of this function is to transmute the receiver object (*this) to make it identical to "other"
-   // Placement new is used to get the vft updated, and constructors on each of the classes identified here
-   //  take care of copying the appropriate data fields. The if nest below covers every concrete subclass of
-   //  IlGeneratorMethodDetails.  If other is not one of these classes, then it will assert.
+   // The if nest below covers every concrete subclass of IlGeneratorMethodDetails.
+   // If other is not one of these classes, then it will assert.
 
    if (other.isOrdinaryMethod())
-      return * new (self()) TR::IlGeneratorMethodDetails(static_cast<const TR::IlGeneratorMethodDetails &>(other));
+      return new (&storage) TR::IlGeneratorMethodDetails(static_cast<const TR::IlGeneratorMethodDetails &>(other));
    else if (other.isDumpMethod())
-      return * new (self()) DumpMethodDetails(static_cast<const DumpMethodDetails &>(other));
+      return new (&storage) DumpMethodDetails(static_cast<const DumpMethodDetails &>(other));
    else if (other.isNewInstanceThunk())
-      return * new (self()) NewInstanceThunkDetails(static_cast<const NewInstanceThunkDetails &>(other));
+      return new (&storage) NewInstanceThunkDetails(static_cast<const NewInstanceThunkDetails &>(other));
    else if (other.isMethodInProgress())
-      return * new (self()) MethodInProgressDetails(static_cast<const MethodInProgressDetails &>(other));
+      return new (&storage) MethodInProgressDetails(static_cast<const MethodInProgressDetails &>(other));
    else if (other.isMethodHandleThunk())
       {
       if (static_cast<const MethodHandleThunkDetails &>(other).isShareable())
-         return * new (self()) ShareableInvokeExactThunkDetails(static_cast<const ShareableInvokeExactThunkDetails &>(other));
+         return new (&storage) ShareableInvokeExactThunkDetails(static_cast<const ShareableInvokeExactThunkDetails &>(other));
       else if (static_cast<const MethodHandleThunkDetails &>(other).isCustom())
-         return * new (self()) CustomInvokeExactThunkDetails(static_cast<const CustomInvokeExactThunkDetails &>(other));
+         return new (&storage) CustomInvokeExactThunkDetails(static_cast<const CustomInvokeExactThunkDetails &>(other));
       }
 
    TR_ASSERT(0, "Unexpected IlGeneratorMethodDetails object\n");
-   return *(self());
+   return NULL; // error case
    }
 
 

runtime/compiler/trj9/ilgen/J9IlGeneratorMethodDetails.hpp

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2017 IBM Corp. and others
+ * Copyright (c) 2000, 2018 IBM Corp. and others
  *
  * This program and the accompanying materials are made available under
  * the terms of the Eclipse Public License 2.0 which accompanies this
@@ -74,10 +74,10 @@ class OMR_EXTENSIBLE IlGeneratorMethodDetails : public OMR::IlGeneratorMethodDet
 
    IlGeneratorMethodDetails(const TR::IlGeneratorMethodDetails & other);
 
-   TR::IlGeneratorMethodDetails & operator=(const TR::IlGeneratorMethodDetails & other);
-
    static TR::IlGeneratorMethodDetails & create(TR::IlGeneratorMethodDetails & target, TR_ResolvedMethod *method);
 
+   static TR::IlGeneratorMethodDetails * clone(TR::IlGeneratorMethodDetails & storage, const TR::IlGeneratorMethodDetails & source);
+
    virtual const char * name() const { return "OrdinaryMethod"; }
 
    virtual bool isOrdinaryMethod()     const { return true; }